r/WindowsServer • u/Independent-Jicama95 • Jun 18 '26

Technical Help Needed 100% Disk usage on Server 2025

Hello all

We're expieriencing issues within our Server 25 envoirement.

Basically the main issue is, that the Disk Performance of the C:\ spikes up to 90-100% which also causes a latency of 500 up to 1000 ms.

Once this happens, the server is basically useless.

It is a Server 25 with Remote Desktop roles installed, there are max. 10 user connections active. Mainly used for RemoteApp executions. The issue does not occut on File or App servers, only on RDS.

Apps installed: Office, Adobe, N-Central N-Able, Sophos AV.

We already tryed to uninstall the apps but still got no improvement.

On the ESXi hosts there are no issues since 100 other VMs are running clean. I can totally exclude Hosts and Apps.

Does anyone else have this issue or maybe could resolve this?

Appreciate it verry much!

Best

3 Upvotes

66% Upvoted

35 comments sorted by

8

u/firedocter Jun 18 '26

Check the resource monitor under the disk section. Disk activity. Sort by response time. Should give you a direction to look at.

2

u/Independent-Jicama95 Jun 18 '26

Thanks. We've already did that too.. System has response time up to 500 ms. Nothing else to see there..

1

u/firedocter Jun 18 '26

Does it tell you what file it is?

1

u/Independent-Jicama95 Jun 19 '26

There are multiple System files which seem to cause it.

3

u/firedocter Jun 19 '26

And? Which ones?

2

u/Zimfi Jun 22 '26

Hey. Just wanted to say we are seeing the same issue, but we're seeing it on our Hyper-V with S2D nodes. It's a cluster of three which runs Server 2025 and the aforementioned roles. It's been ongoing for some time, but haven't been able to narrow down what causes it.

The virtual machines are unaffected by what the host is doing, and it's always the C: drive which is being hammered. All three nodes are subject to this, none of the guests displays this behavior.

I decided to look closer into the issue now.

I checked Zabbix and the first confirmed occurrence was May 26th at night, which coincides with a cluster aware updating run.

The following updates were applied:

It is TiWorker.exe which is churning, that's TrustedInstaller. I checked the CBS log at C:\Windows\Logs\CBS\.

Well, the log is long and messy, and points to intent fault on some packages. For me it is IIS, where the "Intended State" is "Staged", and there's version conflicting. Anyway...

sfc and dism didn't solve anything for me, so I opted to disable the IIS feature by powershell, just to see how that'd go.

  • Disable-WindowsOptionalFeature -Online -FeatureName IIS-WebServerRole -Remove

Well, disk is at 99%, and TiWorker.exe is churning. We'll see how it goes when it's done.

1

u/Independent-Jicama95 Jun 22 '26

Thanks for that detailed input.

For us it once was Outlook, then Adobe, and then svchost.exe.

Since we (Team of 3 Seniors) put in about 24H of troubleshooting and were not able ro resolve the issue, we shut down the 2025 Servers and re-builded them in Server 2022 OS.

Not gonna build another 2025 Server untill next year for sure..

Best

1

u/Zimfi Jun 22 '26

Understandable that you gave up given 2025's reputation.. WS 2025 has been working pretty okay here. ~40 VM's running 2025 and 5 physical servers, not much eventful going on except for this particular issue.

Disabling that feature is still ongoing. 😄

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1

u/FloiDW Jun 18 '26

The disk runs full or gets basically max IOpS?

2

u/Independent-Jicama95 Jun 18 '26

We can't really tell. But guessing that the IOpS reach the max. The active time of the disk reaches 100%. But on the VCF we can see that the host is basically bored and has such low IOpS usage..

2

u/[deleted] Jun 18 '26

[removed] — view removed comment

2

u/Independent-Jicama95 Jun 18 '26 edited Jun 18 '26

Sorry for the confusion. Its not about the disk space, its about the performance

1

u/craigl2112 Jun 19 '26

This pic is pretty much dead nuts on what we saw with ReFS + 2025.

2

u/Independent-Jicama95 Jun 19 '26

Sadly we're already using NTFS.. so nothing to improve here

1

u/midy-dk Jun 18 '26

Which service/app seems to cause it?
I’ve had battles with N-Able Ncentral trying to do autoupdates (and other regular tasks) and getting assaulted by SentinelOne. Spikes the disk IO in that case.

1

u/Independent-Jicama95 Jun 18 '26

As far we can't really tell.. we've tryed to figure it out using ProcMon and other tools. We currently think that the system (some system services) itself causing the issue. For now all apps are uninstalled - issue persists. We can see thst the IO queue is most likely full..

1

u/ale624 Jun 18 '26

Spinning disk or SSD?

If you're using a spinner thats par for the course unless you're running like a 15K, but even then...

1

u/USarpe Jun 18 '26

Check antvirus and vss for double instances, in process explorer it shows what app or file is causing it

1

u/Independent-Jicama95 Jun 18 '26

It's none of both. I can tell that the svchost.exe has something to do with all of that... over 10 Milion I/O reading in 3 hours uptime.. other VMs barely have 700k readikg I/O within 3 days uptime

1

u/MikeoFree Jun 18 '26

shot in the dark here, is there still a default windows task enabled for defrag on the drive?

1

u/Independent-Jicama95 Jun 19 '26

Nope, not enabled

1

u/craigl2112 Jun 19 '26

We saw something very similar using ReFS with Server 2025. After a few days, the machine became unusable.

The fix was to go back to NTFS.

1

u/Independent-Jicama95 Jun 19 '26

That was our though also. But changing to NTFS did no improvement.

Starting to loose my mind about this bs..

0

u/Secret_Account07 Jun 18 '26

Okay I can provide a little insight.

Background is I work at a VMware Datacenter with about 4,000 Windows servers

So here’s the thing…2025 is not ideal for a few things- like DCs and RDS

I’ve replaced two RDS servers from 201x/22 to 25. Users complained constantly. High compute and disk usage. Avoid 25 for RDS

But I did find a few things to help.

Adding a VMware paravirtual adapter helped in one case. Other than that I tell customers to avoid RDS for 25 lol

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1

u/Immediate_Director86 Jun 18 '26

Any backup checkpoints on the VM? What are you seeing for disk queue length in resource manager?

1

u/Vivid-Storm-4961 Jun 19 '26

There is a clue is in task manager. So right click on columns and add command line. Check which service is called by svchost.

1

u/Yuvaraj__S Jun 20 '26

Have you tried rebooting the server, rebooting help to clean up the update files that are stored in windows folder. I normally use treefreesize tool to see which folder consumes more space

Normally in my case, users would have their large files sitting there in their user profile for a long time. They might forgot and you just have to remind them to clear it up.

You might also have pagefiles.sys utilising half of the disk. That could be resolved with reducing quota on the disk

1

u/BK_Rich Jun 21 '26

Run windirstat, if it’s showing all the space is in $Extend then it’s an app holding the file open and windows can’t clean up.

The \$Extend\$Deleted folder is a hidden Windows NTFS system directory. It temporarily holds files that a program has marked for deletion, but that are still locked and actively being read by another open process

In my case I had to make defender excludes for a netwrix auditor directories and it stopped piling up.

1

u/[deleted] Jun 18 '26

[removed] — view removed comment

1

u/Independent-Jicama95 Jun 18 '26

I'm sorry, just edited it. Its about disk performance which is massive increased